[Bacterial strain characterizing by EDTA requirement].

A novel strain of bacteria (LPM-4) was isolated that is characterized by a unique EDTA requirement for cell growth. Suspensions of washed cells of strain LPM-4 degrated EDTA complexes with Ba2+, Mg 2+, Ca2+, and Mn2+ at constant rates (0.310-0.486 mmol EDTA/(g h)) and Zn-EDTA at an initial rate of 0.137 +/- 0.016 mmol EDTA/(g h). The temperature optima for cell growth and EDTA degradation were determined under pH-auxostat cultivation. As compared with the known EDTA-degrating bacteria, strain LPM-4 exhibited a higher specific growth rate (0.095 h(-1)) and lower mass cell yield (0.219 g cells/g EDTA) that is promising for its practical applications for EDTA removal in wastewater treatment plants.

[Bacterial degradation of EDTA]. / Issledovanie bakterial'noi degradatsii EDTA.

Degradation of EDTA (ethylenediaminetetraacetic acid) or metal-EDTA complexes by cell suspensions of the bacterial strain DSM 9103 was studied. The activity of EDTA degradation was the highest in the phase of active cell growth and decreased considerably in the stationary phase, after substrate depletion in the medium. Exponential-phase cells were incubated in HEPES buffer (pH 7.0) with 1 mM of uncomplexed EDTA or EDTA complexes with Mg2+, Ca2+, Mn2+, Pb2+, Co2+, Cd2+, Zn2+, Cu2+, or Fe3+. The metal-EDTA complexes (Me-EDTA) studied could be divided into three groups according to their degradability. EDTA complexes with stability constants K below 10(16) (lg K < 16), such as Mg-EDTA, Ca-EDTA, and Mn-EDTA, as well as uncomplexed EDTA, were degraded by the cell suspensions at a constant rate to completion within 5-10 h of incubation. Me-EDTA complexes with lg K above 16 (Zn-EDTA, Co-EDTA, Pb-EDTA, and Cu-EDTA) were not completely degraded during a 24-hour incubation, which was possibly due to the toxic effect of the metal ions released. No degradation of Cd-EDTA or Fe(III)-EDTA by cell suspensions of strain DSM 9103 was observed under the conditions studied.

[Growth-coupled lipid synthesis in Mortierella alpina LPM 301, a producer of arachidonic acid]. / Sopriazhennyi s rostom sintez lipidov u produtsenta arakhidonovoi kisloty Mortierella alpina LPM-301.

Mortierella alpina LPM 301, a producer of arachidonic acid (ARA), was found to possess a unique property of intense lipid synthesis in the period of active mycelium growth. Under batch cultivation of this strain in glucose-containing media with potassium nitrate or urea, the bulk of lipids (28-35% of dry biomass) was produced at the end of the exponential growth phase and remained almost unaltered in the stationary phase. The ARA content of lipids comprised 42-50% at the beginning of the stationary phase and increased continuously after glucose depletion in the medium due to the turnover of intracellular fatty acids; by the end of fermentation (189-210 h), the amount of ARA reached 46-60% of the total fatty acids (16-19% of dry mycelium). Plausible regulatory mechanisms of the growth-coupled lipid synthesis in microorganisms are discussed.

Application of mass and energy balance regularities in fermentation. Reprinted from Biotechnology and Bioengineering, Vol. XX, No. 10, Pages 1595-1621 (1978).

Material and energy balances for fermentation processes are developed based on the facts that the heat of reaction per electron transferred to oxygen for a wide variety of organic molecules, the number of available electrons per carbon atom in biomass, and the weight fraction carbon in biomass are relatively constant. Mass-energy balance equations are developed which relate the biomass energetic yield coefficient to sets of variables which may be determined experimentally. Organic substrate consumption, biomass production, oxygen consumption, carbon dioxide production, heat evolution, and nitrogen consumption are considered as measured variables. Application of the balances using direct and indirect methods of yield coefficient estimation is illustrated using experimental results from the literature. Product formation is included in the balance equations and the effect of product formation on biomass yield estimates is examined. Application of mass-energy balances in the optimal operation of continuous single-cell protein production facilities is examined, and the variation of optimal operating conditions with changes in yield are illustrated for methanol as organic substrate.

[Effect of conditions od Trichosporon pullulans culturing on the synthesis of immunomodulating glycoprotein]. / Vliianie usloviu kul'tivirovaniia Trichosporon pullulans na sintez glikoproteina-immunomoduliatora.

An extracellular glycoprotein (GP) exhibiting immunomodulating activity produced by the yeast Trichosporon pullulans grown in a defined ethanol-containing medium differed substantially in its composition from that of the yeast cell walls: therefore, it cannot be considered a structural component of the cell walls. In batch culture, the greatest GP production (40 mg/l) occurred in the exponential phase of the yeast growth. Under continuous cultivation, in both chemostat and pH-auxostat regimes, the specific rate of GP synthesis (qGP) increased with the increasing specific growth rate (mu) and reached 1.55 mg/(g h) at mumax. Under limitation of the yeast growth by zinc qGP was three times lower than under nitrogen or iron limitation. The rate of GP production depended inversely on the oxygen concentration.

Arachidonic-acid production by species of Mortierella.

A growth-inhibiting, aspirin-containing medium was developed to select arachidonic-acid-(ARA)-producing Mortierella species and to determine the fatty-acid content of 87 Mortierella strains. ARA was detected in 66 strains from 33 species and its production may prove useful for systematic studies on Mortierella spp. The ARA content of the 66 producing strains tested ranged from 4% to 55% of total lipids. Most of the ARA-producing strains of Mortierella (59 strains) grown on potato/glucose/agar synthesized <20% ARA. Four strains produced between 20% and 25% ARA and three produced >40%. An inverse relationship was observed between ARA and oleic-acid contents.

[The effect of autolysis on characteristics of amino acid mixtures, obtained using ethanol-assimilating yeasts]. / Vliianie uslovii avtoliza na kharakteristiki aminokislotnykh smesei, poluchennykh s ispol'zovaniem étanolassimiliruiushchikh drozhzhei.

The influence of the enzyme preparation - macerate, concentration of the yeast biomass in the reaction medium, and chloroform on the autolysis of the ethanol assimilating yeast Saccharomyces cerevisiae BKM-Y-2656, BKM-Y-2465, and the baker's yeast r. L-2 was studied. Amino acid mixtures were isolated from the yeast autolysates. The use of macerate and a decrease in the biomass concentration were shown to increase the yield of the amino acid mixtures. The use of chloroform positively influenced the baker's yeast autolysis. Conditions of the joint action of these factors on the intensification of the process of the amino acid mixtures preparation based on the autolysis were determined.

[Inhibition of Candida valida growth by copper ions]. / Ingibirovanie rosta Candida valida ionami medi.

The high toxicity of copper ions for Candida valida growth was established at pH-auxostat regime. The value of mu max decreased even at the residual Cu2+ concentration 1.0 mg/l. The inhibition constant (Ki) that characterized a copper ion concentration at which yeast specific growth rate was halved was equal to 7.7 mg/l. A linear dependence of 1/mu max on a residual concentration of copper ions indicates that yeast growth inhibition is due to inhibition of one enzymic reaction which is the most sensitive to copper. Yeast growth inhibition by copper was accompanied by accumulation of Cu2+ ions in biomass, a decrease in nucleic acid and true protein contents, and changes in amino acid composition of protein. The amounts of cystine and cysteine in protein increased and tryptophane content decreased with inhibition of yeast growth. Yeast growth inhibition by copper did not affect the lipid content but significantly reduced the degree of unsaturation due to a decrease in the amounts of polyunsaturated linoleic and alpha-linolenic acids.

Bistat--a novel method of continuous cultivation.

Bistat is the method of continuous cultivation developed on the basis of pH-auxostat. It provides the stability of cultivation in each point of mu(S) dependence. This article describes the principle of bistat operation, the theory of bistat dynamics, its instrumentation, and some experimental results.

[Mechanism of Hansenula polymorpha reaction to the pulsed addition of a limiting substrate]. / O mekhanizme reaktsii Hansenula polymorpha na impul'snuiu dobavku limitiruiushchego substrata.

As was shown in experiments with a Hansenula polymorpha culture, a temporary drop in the pH of the medium in response to a pulse addition of a limiting substrate (organic or mineral) is not related to NH4+ uptake from the medium. The response is similar in media with NH4+ and in distilled water without NH4+. The pH drop caused by a pulse addition of certain substrates appears to result from the extrusion of H+ ions in the process of antiport: K+/H+ and Mg2+/H+. It is likely that the response to a substrate pulse is the extrusion of H+ ions for maintaining the membrane potential decreased owing to the uniport of either NH4+ or K+. Protons may be extruded in response to a substrate pulse during glycolysis of respiration. It is possible that an addition of organic substrates activates the metabolism; inorganic ions may also have a stimulating action. The lag time from the moment of substrate addition to the beginning of a decrease in the pH of the medium seems to include transport to the cytoplasmic membrane, transport into the cell and, possibly, the first steps of metabolism of the added substrate.

[Microorganisms as potential producers of essential fatty acids]. / Mikroorganizmy kak potentsial'nye produtsenty nezamenimykh zhirnykh kislot.

The data on the importance of essential fatty acids in a balanced diet have been considered. The ways of essential fatty acid synthesis in microorganisms and their metabolism in animal tissues are being discussed. The criteria for microorganisms selection--producers of food lipids have been proposed.

Efficiency of lipid synthesis by yeasts.

The efficiency of lipid synthesis by ethanol-grown yeasts is characterized using the coefficient of the lipid energetic yield (eta(1)). This coefficient is defined as the fraction of energy in an organic substrate that is converted to lipids. The advantages of eta(1) compared with the "fat coefficient" (F(s)) as well as the biomass energetic yield (eta) compared with Y(s) are discussed.

[Effect of the growth rate on the biomass composition of Candida valida]. / Vliianie skorosti rosta na sostav biomassy u Candida valida.

The effect of growth rate on the biomass composition was studied with a thermotolerant strain of the yeast Candida valida grown in the chemostat at limitation of the growth by ethanol under the conditions of various temperature regimes. The temperature and the growth rate hardly influenced the content of protein and its amino acid composition. An increase in the specific growth rate of the cells caused a rise in the pool of free intracellular amino acids, in particular, glutamic acid. The degree of lipid unsaturation increased with a rise in the growth rate of the yeast as a result of intensification of oleic acid oxidative dehydration. As it had been shown earlier, the content of nucleic acids increased with a rise in the specific growth rate of the yeast.

[Biomass composition of thermotolerant yeasts of the genus Candida under elevated cultivation temperatures]. / Sostav biomassy termotolerantnykh drozhzhei roda Candida pri povyshennykh temperatureakh kul'tivirovaniia.

The effect of growth temperature on the content of nucleic acids, the content and composition of protein, and the pool of free amino acids and lipids was studied under the conditions of chemostat cultivation of yeast strains at constant flow rates and pO2. The pool of free amino acids in all of the strains decreased with an increase in the temperature of growth. Changes in the content and composition of other cellular components depending on temperature were determined by individual characteristics of the strains. A linear relationship between the content of biomass components and the temperature of growth was found only in Candida scottii. The temperature of yeast cultivation may be used as a factor regulating the pool of free intracellular amino acids and the fatty acids composition of lipids.

[Relationship between continuous cultivation conditions and the lipid composition of Hansenual polymorpha]. / Sostav lipidov Hansenula polymorpha v zavisimosti ot uslovii nepreryvnogo kul'tivirovaniia.

The effect of temperature, pH, and specific growth rate on the composition of fatty acids and lipid classes was studied in the thermotolerant yeast Hansenula polymorpha grown in the chemostat in a medium with methanol. The fatty acid composition of lipids was found to change depending on the conditions of cultivation: the degree of unsaturation of fatty acids increased when the growth temperature decreased; the proportion of linoleic acid in the lipids increased with the specific growth rate of the yeast and with the pH of the medium. The composition of lipid classes also depended on the cultivation conditions. Therefore, it is possible to find such a regime for cultivating the yeast that would be optimal for the accumulation of particular lipid classes.

[Identification of the limiting component of the medium during microbial continuous cultivation]. / Proverka limitiruiushchego komponenta sredy v protsesse neprerbvnogo kul'tivirovaniia mikroorganizmov.

The paper presents a method allowing a rapid identification of the growth limiting component of the medium. This is done with respect to the fast change in the low inertial parameter of fermentation (rate of titration or oxygen consumption) in response to an insignificant variation of the concentration of the growth limiting nutrient component in the fermentation medium.

[Effect of cell metabolism on the rate of medium addition during pH stabilized cultivation]. / Vliianie metabolizma kletok na skorost' podachi sredy pri pH-statirovannom kul'tivirovanii.

The rate of base or acid addition to the culture broth for maintenance of the present pH-value is a quantity reflecting the metabolic activity of the cell population. This quantity is proportional to the biomass growth rate with the proportionality coefficient depending on the cell consumption of ionized substrates from the environment, cell biomass, electric charge, and content of ionized metabolic products in the medium. The equation for this relationship has been found and the effect of the above, factors on the titration rate has been calculated. This rate may be used to obtain rapidly the quantitative information on the growth of the cell population.

[Induced methanol dehydrogenase in the yeast Hansenula polymorphia DL-1]. / Indutsiruemaia metanoldegidrogenaza v drozhzhakh Handenula polymorpha DL-1.

The yeast Hansenula polymorpha DL-I showed NAD-specific dehydrogenase activity involved in the methanol primary oxidation. This enzyme was found to be induced during periodic and continuous H. polymorpha cultivation, using methanol as the sole source of carbon and energy. The enzyme was absent during yeast cultivation on the glucose and ethanol containing medium.

[Growth efficiency and the specific rate of the yeast Hansenula polymorpha during continuous cultivation on methanol]. / Izuchenie effektivnosti i udel'noi skorosti rosta drozhzhei Hansenula polymorpha na metanole pri nepreryvnom kul'tivirovanii.

The growth of Hansenula polymorpha DL-1 in the chemostat (under methanol limitation) and turbidostat was measured. Cultivation with different specific rates of growth mu made it possible to determine the maximum yield of biomass Ys(max)=0.425 and the level of expendables required to maintain Ms=0.023 hr-1. The following parameters describing mu as a function of the concentration of methanol S in the fermenter were found: muo=0.154 hr-1 (maximum growth rate), Ks=1.31 mg/l, Ki=5.35 g/l. The paper emphasizes a very low value of the saturation constant Ks derived from the above experiments and reviews the literature data on the kinetic characteristics of various methanol-grown yeast.